In this project we plan to use longitudinal observational data and human genetics to examine the relationship and discordances between BMI and both perceived and desired body size in a sample of pre-pubertal children. We additionally want to understand the association between BMI and body image dissatisfaction (BID) (the difference between perceived and desired body size) in childhood and disordered eating and self-harm in adolescence. Finally, we are interested in the mechanisms by which BMI and BID affect disordered eating and self-harm.